Chromis cyanea. The Blue Chromis is a very peaceful and active fish from the Caribbean. These fish reside in the upper part of the aquarium and will help bring out more shy species that normally hide. A shoaling fish, Blue Chromis should be maintained together in a group, and make a bright addition to the reef or fish only aquarium that is 30 gallons or larger. The Blue Chromis feeds on a variety of meaty items, herbivore preparations, and flaked food. The diet should be varied and consist of meaty items, herbivore flakes, and frozen preparations. Using vitamin-enriched foods may help to preserve the bright color.